Constipation, very shy and quiet 13 yrs old

Hi,

I have a 13 yrs old daughter, she passes stool once every 3-4 days. She doesn't complain for any stomach pain. She says it doesn't hurt when she passes stool. She feels no urge to pass stools. When she goes it's just one bulk and she gets up right away. In 1 minute she is done. She feels full mostly and has no interest in eating. She is very shy and quiet by nature. She has been like that always. She is very intelligent, and helpful to others in studies. It's very hard for her to wake up in the morning. On the days she has no school, she will not wake up by herself, and usually wakes up by 11am. She doesn't get involved with family much. She feels content with herself. She has a younger sister too, and they get along well, she helps her in homework too. They play together well. But she doesn't get invoved in any social situation or discussion, those times she'll just be very quiet and shy.

Please suggest a remedy for her constipation, and shy nature if possible.

Thanks,
Pooja